Wireless telecommunication systems are well known in the art. Wireless systems require an available bandwidth in which to operate. Typically, the permission to use a portion of the available spectrum for wireless communication for a particular geographic region is obtained from an appropriate governmental unit of the physical territory in which the wireless communications are to be conducted. In order to make efficient use of limited spectrum available for operation of a wireless telecommunication system, Code Division Multiple Access (CDMA) systems have been developed which include Time Division Duplex (TDD) modes which provide a very flexible framework for providing concurrent wireless communication services. Supported wireless communication services can be any of a variety of types including voice, fax, and a host of other data communication services.
In order to provide global connectivity for CDMA systems, standards have been developed and are being implemented. One current standard in widespread use is known as Global System for Mobile Telecommunications (GSM). This was followed by the so-called Second Generation mobile radio system standards (2G) and its revision (2.5G). Each one of these standards sought to improve upon the prior standard with additional features and enhancements. In January 1998, the European Telecommunications Standard Institute - Special Mobile Group (ETSI SMG) agreed on a radio access scheme for Third Generation Radio Systems called Universal Mobile Telecommunications Systems (UMTS). To further implement the UMTS standard, the Third Generation Partnership Project (3GPP) was formed in December 1998. 3GPP continues to work on a common third generational mobile radio standard.
A typical UMTS system architecture in accordance with current 3GPP specifications is depicted in FIGS. 1 and 2. The UMTS network architecture includes a Core Network (CN) interconnected with a UMTS Terrestrial Radio Access Network (UTRAN) via an interface known as IU which is defined in detail in the current publicly available 3GPP specification documents.
The UTRAN is configured to provide wireless telecommunication services to users through User Equipments (UEs) via a radio interface known as UU. The UTRAN has base stations, known as Node Bs in 3GPP, which collectively provide for the geographic coverage for wireless communications with UEs. In the UTRAN, groups of one or more Node Bs are connected to a Radio Network Controller (RNC) via an interface known as Iub in 3GPP. The UTRAN may have several groups of Node Bs connected to different RNCs, two are shown in the example depicted in FIG. 1. Where more than one RNC is provided in a UTRAN, inter-RNC communication is performed via an Iur interface.
A UE will generally have a Home UMTS Network (HN) with which it is registered and through which billing and other functions are processed. By standardizing the Uu interface, UEs are able to communicate via different UMTS networks that, for example, serve different geographic areas. In such case the other network is generally referred to as a Foreign Network (FN).
Under current 3GPP specifications, the Core Network of a UE's HN serves to coordinate and process the functions of Authentication, Authorization and Accounting (AAA functions). When a UE travels beyond its Home UMTS Network, the HN's Core Network facilitates the UE's use of a Foreign Network by being able to coordinate the AAA functions so that the FN will permit the UE to conduct communications. To assist in implementing this activity, the Core Network includes a Home Location Register (HLR) which tracks the UEs for which it is the HN and a Visitor Location Register (VLR). A Home Service Server (HSS) is provided in conjunction with the HLR to process the AAA functions.
Under current 3GPP specifications, the Core Network, but not the UTRAN, is configured with connectivity to external systems such as Public Land Mobile Networks (PLMN), Public Switch Telephone Networks (PSTN), Integrated Services Digital Network (ISDN) and other Real Time (RT) services via an RT service interface. A Core Network will also support Non-Real Time services with the Internet. External connectivity of the Core Network to other systems, enables users using UEs to communicate via their Home UMTS Network, beyond the area served by the HN's UTRAN. Visiting UEs can likewise communicate via a visited UMTS Network, beyond the area served by the visited UMTS's UTRAN.
Under current 3GPP specifications, the Core Network provides RT service external connectivity via a Gateway Mobile Switching Center (GMSC). The Core Network provides NRT service, known as General Packet Radio Service (GPRS), external connectivity via a Gateway GPRS Support Node (GGSN). In this context, a particular NRT service may actually appear to a user to be a real time communication due to the communication speed and associated buffering of the TDD data packets forming the communication. One example of this is voice communication via the Internet which can appear to the user as a normal telephone call conducted by a switching network, but is actually being conducted using an Internet Protocol (IP) connection which provides Packet data Service.
A standard interface known as GI is generally used between a CN's GGSN and the Internet. The GI interface can be used with Mobile Internet Protocols, such as Mobile IP v4 or Mobile IP v6 as specified by the Internet Engineering Task Force (IETF).
Under current 3GPP specifications, to provide support for both RT and NRT services from external sources for radio linked UEs in a 3GPP system, the UTRAN must properly interface with the CN which is the function of the Iu interface. To do this, the Core Network includes a Mobile Switching Centre (MSC) that is coupled to the GMSC and a Serving GPRS Support Node (SGSN) that is coupled to the GGSN. Both are coupled with the HRL and the MSC is usually combined with the Visitor Location Register (VLR).
The Iu interface is divided between an interface for Circuit Switched communications (Iu-CS) and an interface for packet data via Packet Switched communications (Iu-PS). The MSC is connected to the RNCs of the UTRAN via the Iu-CS interface. The Serving GPRS Support Node (SGSN) is coupled to the UTRAN's RNCs via the Iu-PS interface for Packet Data Services.
The HLR/HSS is typically interfaced with the CS side of the Core Network, MSC and GMSC via an interface known as Gr which supports AAA functions through a Mobile Application Part (MAP) Protocol. The SGSN and the GGSN of the CN are connected using interfaces known as Gn and Gp.
Common to 3GPP systems and other systems which utilize TDD-CDMA telecommunications, such as some GSM systems, is the aforementioned division of connectivity between the radio network and the Core Network. In general, the radio network, i.e. the UTRAN in 3GPP, communicates via a wireless interface with UEs and the Core Network communicates with external systems via RT and NRT service connections. Applicants have recognized this standardized type of architecture is most likely the result of the processing of the AAA functions in the Core Network. However, applicants have further recognized that even if the AAA functions are to be maintained in the Core Network, significant advantages and benefits can be obtained by providing direct connectivity from a TDD-CDMA radio network to the Internet.
In particular, Applicants have recognized that the existing separation of functions of the Iu interface defined in 3GPP for Circuit Switched (CS) communications used with Real Time services (Iu-CS interface) and defined in 3GPP for Packet Switch (PS) service used with Non-Real Time services (Iu-PS interface), enables one to easily provide an IP Gateway in the UTRAN for enabling the UTRAN to direct connectivity to the Internet bypassing use of a Core Network for this function. Moreover, as a result, Applicants have recognized that by permitting direct access to the Internet from the UTRAN, a Radio Local Area Network is defined that can provide significant benefits and advantages for use with or without a Core Network.
Further detail of a typical 3GPP system is illustrated in FIG. 3. The UTRAN segment of a conventional UMTS architecture is split it into two traffic planes known as the C- and U- planes. The C-plane carries control (signaling) traffic, and the U-plane transports user data. The over-the-air segment of the UTRAN involves two interfaces: the Uu interface between UE and Node B, and the Iub interface between the Node B and RNC. As noted above, the back-end interface between the RNC and core network is referred to as the Iu interface, split into the Iu-CS for the circuit-switched connection into the MSC, and the Iu-PS for the packet-switched connection into the SGSN.
The most significant signaling protocol on the over-the-air segment of the UTRAN is Radio Resource Control (RRC). RRC manages the allocation of connections, radio bearers and physical resources over the air interface. In 3GPP, RRC signaling is carried over the Radio Link Control (RLC) and Medium Access Control (MAC) UMTS protocols between the UE and RNC. Overall, the RNC is responsible for the allocation/de-allocation of radio resources, and for the management of key procedures such as connection management, paging and handover. Over the Iub interface, RRC/RLC/MAC messaging is typically carried on a Transport Layer via Asynchronous Transfer Mode (ATM), using the ATM Adaptation Layer Type 5 (AAL5) protocol over the ATM physical layer with intermediary protocols, such as Service Specific Co-ordination Function (SSCF) and the Service Specific Connection Oriented Protocol SSCOP, being used above AAL5.
U-plane data (e.g. speech, packet data, circuit-switched data) uses the RLC/MAC layers for reliable transfer over the air interface (between UE and RNC). Over the Iub segment, this data flow (user data/RLC/MAC) occurs over UMTS-specified frame protocols using the ATM Adaptation Layer Type 2 (AAL2) protocol over the ATM physical layer running (AAL2/ATM).
The Iu interface carries the Radio Access Network Application Part (RANAP) protocol. RANAP triggers various radio resource management and mobility procedures to occur over the UTRAN, and is also responsible for managing the establishment/release of terrestrial bearer connections between the RNC and SGSN/MSC. RANAP is carried over AAL5/ATM, with intermediary Signaling System 7 (SS7) protocols, such as Signaling Connection Control Part, Message Transfer Part (SCCP/MTP) on top of SSCF and the Service Specific Connection Oriented Protocol (SSCOP), being used above AAL5. Internet Protocol is typically used over AAL5/ATM for the Iu-PS interface so that the intermediate Stream Control Transmission Protocol (SCTP) is then used over IP. Where multiple RNCs exist in a UTRAN which have an Iur interface, IP is also commonly used over ATM and intermediate protocols include SSCP, SCTP and the Message Transfer Part level 3 SCCP adaptation layer of SS7 (M3UA) that have been developed by IETF.
For the U-Plane, between the UTRAN and the CN, circuit-switched voice/data traffic typically flows over AAL5/ATM, via the Iu-CS interface, between the RNC and MSC. Packet-switched data is carried over the Iu-PS interface between the RNC and SGSN, using the GPRS Tunneling Protocol (GTP) running over the User Data Protocol for the Internet Protocol (UDP/IP) over AAL5/ATM.
Applicants have recognized that this architecture can be improved upon in connection with providing direct IP connectivity for the UTRAN.